Yep its baking soda.
The pH of my tank is between 8.2 and 8.4 and I got like 7.8 - 8.
Its been approx 1 hour that I mixed the water.
I'm pretty sure the test kit is good, I just bought it like 1 week ago.

OK...chemistry 101 time here. That much baking soda would have reacted with the calcium and magnesium and precipitated out. leaving a white caking on the container and residue in the bottom. Baking soda will not raise pH in saltwater...it will raise the carbonate hardness and alkalinity and then that in turn will precipitate out if it is out of balance with the calcium and magnesium. If this is makeup water for a water change do not even bother testing it for at least 12 hours of mixing. There is usually no need to worry with pH as commercial salt mixes will already have the proper buffers in them. What you have in that bucket now is highly alkaline water with little to no calcium and magnesium.

Basically you need to dump that, clean the residue off the container and start over...this time do not adjust the water unless you are experienced with water chemistry and are trying to keep sps corals and matching the tank conditions. Leave the saltmix alone, it will be close enough._________________Out on the road today...I saw a DeadHead sticker on a Cadillac...
Jack
110 Gallon DSA Pentagon

By the way...welcome to the chemistry side of saltwater. We all have made mistakes and we will all continue to make them._________________Out on the road today...I saw a DeadHead sticker on a Cadillac...
Jack
110 Gallon DSA Pentagon

Baking soda is great for adding alkalinity but not so good for raising pH. Add too much baking soda and you have a very messed up balance._________________Out on the road today...I saw a DeadHead sticker on a Cadillac...
Jack
110 Gallon DSA Pentagon

Atlantis;
Caution is in order here; please take time to research/understand the potential for pH shock associated with rapid shifts and the dangerous impact it can have on your livestock:
http://www.wetwebmedia.com/marphalk.htm_________________Keepin' marines happy for 25 years

Not even...3 years ago I had to start learning this stuff when my fascination with corals began._________________Out on the road today...I saw a DeadHead sticker on a Cadillac...
Jack
110 Gallon DSA Pentagon